Apparatus for projecting a molten material into a cooling medium

ABSTRACT

A crucible holding a liquid raw material such as molten steel is enclosed in a pressurization chamber. A nozzle in contact with the raw material projects the raw material into a cooling fluid to form a solid finished product. A gasket formed of a material which is gas-tight and compatible with the raw material is mounted for contact with the raw material and has a portion extending away therefrom. The raw material facilitates a hot seal between (a) the portion of the gasket in contact therewith and (b) the crucible and nozzle. A cold seal is formed between (a) the portion of the gasket extending away from the raw material and (b) the pressurization chamber.

United States Patent Massoubre 1 July 29, 1975 [54] APPARATUS FOR PROJECTING A MOLTEN 3.850.225 11/1974 McNitt ct al. 164/82 MATERIAL INTO A COOLING MEDIUM 75 I M M b Primary ExaminerGerald A. Dost 1 mentor if? g f Attorney, Agent, or Firm Brumbaugh, Graves,

ermonterran rance Donohue & Raymond [73] Assignee: Compagnie Generale des Etablissements Michelin, raison [57] A S R C Soclale Mlchelm & A crucible holding a liquid raw material such as mol- C1ermOmFerrand*France ten steel is enclosed in a pressurization chamber. A [22] Fil d; J 25, 1974 nozzle in contact with the raw material projects the raw material into a cooling fluid to form a solid fin- [21] Appl. No.: 483,008

ished product. A gasket formed of a material which is gas-tight and compatible with the raw material is 52 US. Cl 164/281; 266/38 mourned for Contact with the raw material and has 11 [51] Int. Cl. C2lc 7/00 Pornon extending y therefrom The raw material [581 Field of Search 266/34 R, 38; 425/6, 7, facilitates a hot l between the portion of the 425/378, 376; 164/82, 281, 283 R gasket in contact therewith and (h) the crucible and nozzle. A cold seal is formed between (a) the portion {56] References Cited of the gasket extending away from the raw material UNITED STATES PATENTS and (b) the pressurization chamber.

1,834,687 12/1931 Davis 425/7 X 17 C i 7 D i Fi 3,327,768 6/1967 Craig et al. 164/281 6 33 i l-LL il-11, r

z, I, I yH/,-; 20 4 2' (I l l/ r /v I I:

PATENTED JUL29I975 SHEET APPARATUS FOR PROJECTING A MOLTEN MATERIAL INTO A COOLING MEDIUM BACKGROUND OF THE INVENTION This invention relates to the treatment of molten raw material and, more particularly, to novel and highlyeffective apparatus for treating a molten raw material which is subjected to a gas under pressure.

Conventional apparatus for this purpose typically comprises the following main parts:

a crucible containing the molten raw material and possibly a heating device for bringing the raw material to, or maintaining it in, the molten or liquid state;

one or more functional elements in contact with the molten raw material, such as a passageway in which a measurement device is inserted, an orifice for sampling or addition of material or energy, and a window for the inspection of the molten raw material; and

a pressurization enclosure capable of withstanding a high internal gas pressure, hermetically enclosing the crucible containing the molten raw material, connected to one or more of the functional elements enumerated above, leaving the outside of the functional element or elements free, and intended to place the molten raw material under gas pressure for its treatment.

The invention relates more particularly to apparatus intended to project a jet of liquid into a medium in which this jet solidifies.

Such apparatus is used in particular for the manufacture, as finished products, of continuous or noncontinuous threads of small diameter, fibers or powdered objects from a raw material brought to the liquid state by heating. The apparatus typically comprises the following main elements:

a crucible containing the molten raw material and a heating device for bringing the raw material to, or maintaining it in, the molten or liquid state;

by way of a functional element, at least one interchangeable extrusion nozzle in contact with the molten raw material and provided with one or more orifices intended to establish the thickness of the liquid jet or jets, the nozzle being possibly arranged in a nozzle holder;

a pressurization enclosure capable of withstanding a high internal gas pressure hermetically enclosing the crucible containing the molten raw material, connected with the nozzle, leaving the outside of the nozzle orifice free, and intended to place the molten raw material under a gas pressure suitable for causing the projeting of the raw material through the orifice of the nozzle; and

a solidification chamber with which the outside of the orifice of the nozzle communicates, containing a fluid, generally a gas, intended to cool the hot liquid jet until it has solidified this generallly gaseous fluid being at a temperature and a pressure which are generally relatively low as compared with the atmosphere, the chamber possibly containing a device for receiving the finished product or products.

In order to obtain a finished product of uniform, welldefined quality, for instance a continuous thread of a given diameter, by means of apparatus of the type which has been briefly described above, it is necessary to exert a constant gas pressure, which may be very high, on the molten raw material. It is also generally advisable to avoid disturbance of the jet of mosten raw material or pollution of the atmosphere of the solidification chamber by leaks of gas coming from the pressurization chamber.

A tight seal is particularly difficult to achieve in the region where the pressurization enclosure connects with the nozzle to provide a passage for the jet, espe cially because of the differences both in temperature and in pressure present at the interfaces between the enclosure, the nozzle means and the solidification chamber.

Solutions such as the following have already been proposed: the nozzle is on the one hand clamped in a nozzle holder of larger dimensions so as to move the zones where the scaling is to be effected away from the source of heat consisting of the molten raw material. On the other hand, the contact in the region where the seal is to be effected is produced by conventional means, for instance machined surfaces having close tolerances. Such solutions are very expensive or ineffective, or even both, particularly when it is desired to project a raw material of very high melting point under a high gas pressure. Moreover, indeed the materials constituting the parts or elements in contact with each other are generally incompatible with machining operations, for instance because of their hardness, brittleness, heterogeneity or porosity.

SUMMARY OF THE INVENTION An object of the present invention is to remedy the drawbacks outlined above, whatever the raw material projected, and the stresses of any kind which result therefrom in the crucible and the nozzle.

In accordance with the invention, apparatus is provided intended to project a molten raw material into a cooling medium iniorder to form a solid finished product therein and comprising a crucible, nozzle means and a pressurization enclosure, the end of the orifice of the nozzle within the pressurization enclosure being in contact with the molten raw material within the crucible, and the pressurization enclosure being provided with an opening which frees the outside of the orifice of the nozzle. The apparatus is characterized in that:

a. a gasket or packing of a material which is both gastight and compatible with the molten raw material is arranged between the molten raw material and the pressurization enclosure;

b. in the region where the gasket extends into the molten raw material, a hot seal formed of the raw material surrounds the end of the gasket and caulks the clearance between the crucible, the gasket and the nozzle; and

c. a sealing element, a so-called cold seal, is arranged between the gasket and the pressurization enclosure.

The operation of the packing in accordance with the invention is as follows:

On the side of the molten raw material, the molten raw material infiltrates into the spaces between the gasket and the neighboring parts to a certain depth and, upon moving away from the heat source constituted by the mass of molten raw material, solidifies, thus creating a gastight seal, referred to as the hot seal;

on the side of the pressurization enclosure; the tightness to gases between the gasket and the pressurization enclosure can be effected in various ways. For example, indeed the, temperature at the enclosure may be maintained sufficiently low that conventional sealing means can be used, which sealing means is known as a cold seal. The means facilitating the cold seal may be formed by brazing, soldering, gluing, etc., and may comprise an elastic, metalloplastic or metallic material, glue or solder, etc. The decrease in temperature can be obtained, for instance, by moving the cold seal sufficiently far away from the hot seal and/or by arranging a cooling element in the region of the cold seal, and preferably in contact with it. The gasket may itself be in direct or indirect contact with a cooling element.

One advantage of the invention is that the hot seal is indifferent to the characteristics, and in particular to the temperature, of the molten raw material, being itself formed of the raw material.

Another advantage is that the invention can be carried out in a manner which is both simple and economical.

In a first embodiment of the invention, the wall of the pressurization enclosure is extended to the level of the molten raw material, this extension of the pressurization enclosure serving on the one hand as a gasket and on the other hand as cold seal.

As the nozzle is in general a body of revolution, another embodiment of the invention comprises a gasket having the shape of a body of revolution provided with a central opening. The gasket has for instance the shape of a cylinder or of a conical frustum open at both ends and is possibly surrounded by a ring at one end. Or the gasket may have a shape of a flat circular ring. These shapes are particularly easy and inexpensive to make.

In another embodiment, the gasket has the shape of a body of revolution without a central opening, for instance of a cylinder or of a cone frustum closed at one end, or simply for example the shape of a flat surface. Gaskets having these shapes afford the additional advantage over the preceding embodiments of permitting the temporary shutting off of the nozzle and of preventing leaks of gas through the nozzle before the starting of the melting of the raw material. These embodiments are of particular interest for the following reasons:

first, the gasket provides a seal that permits a vacuum to be produced in the pressurization enclosure;

second, the melting can be started under pressure without leakage, particularly through the orifice of the nozzle.

When the melting point is reached, it is sufficient to cause the portion of the gasket covering the orifice of the nozzle to disappear in order to provide free passage for the flow of molten raw material. For this purpose, one can use, for instance, a gasket which melts at the melting point of the molten raw material, or a gasket of a thickness such that it yields under a certain pressure.

The gasket in accordance with the invention can be made of widely different homogeneous or heterogeneous materials, whether or not reinforced, and whatever their method of production, provided that they are gas-tight and compatible with the moltenraw material.

In particular, when the molten raw material is a metal or a metal alloy, it is advantageous to use as material for the gasket either the metal or alloy itself, or the metal constituting the main element or one of the main elements of the alloy.

It may also be advantageous in certain cases to use as material for the gasket compounds of metals and/or nonmetals, particularly their refractory compounds, for instance silica, silicates, alumina, beryllium oxide or boron nitride, this enumeration of materials being exemplary and not limitative.

BRIEF DESCRIPTION OF THE DRAWING A better understanding of the invention may be gained by reference to the following detailed description of the preferred embodiments thereof and to the appended figures of the drawing, wherein:

FIG. 1 is a diagrammatic axial section of a representative embodiment of apparatus constructed in accordance with the invention and comprising a first form of packing or gasket;

FIG. 2 is a fragmentary view in axial section on a larger scale of a preferred embodiment of another embodiment of apparatus including a gasket in accordance with the invention;

FIGS. 3 to 5 are views similar to FIG. 2 showing other embodiments of apparatus comprising gaskets in accordance with the invention;

FIG. 6 is a fragmentary view in axial section on a larger scale than FIG. 3, illustrating the operation of the gasket shown in FIG. 3; and

FIG. 7 is a fragmentary view in axial section of an embodiment of the invention in which the gasket is formed by an extension of the pressurization enclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a crucible l filled with molten raw material 2. In the crucible 1 there is arranged nozzle means 3, 4 comprising a nozzle proper 3 in its nozzle holder 4. The crucible 1 is enclosed in a pressurization enclosure or chamber 6 provided with a pressure-gas inlet 7, the ultimate source of the gas not being shown. The nozzle holder 4 rests on a cooling element 8 which is connected to the pressurization enclosure 6, a tight seal between these two elements being ensured by means of a seal 9. The cooling of the element 8 is effected by circulation of a cooling fluid in a channel 10. The cooling element 8 comprises an axial opening 11 to provide passage for a jet 12 of the molten raw material 2 which is projected from the outer orifice 13 of the nozzle 3 into a solidification chamber 14, part of which is shown.

As FIG. 1 shows, a packing or gasket 20 has one end 21 in contact with the raw material 2. The other end 22 is in contact with the cooling element 8 of the pressurization enclosure 6 and with the seal 23.

FIG. 2 shows in greater detail an embodiment of the invention comprising a gasket 20 which does not cover or mask the upper orifice 24 of the nozzle 3. In order to illustrate clearly the relation between the gasket 20, the nozzle means 3, 4, the crucible l and the cooling element 8, the clearances 25 between the gasket 20 and the elements with which it is in contact have been relatively exaggerated. Ordinarily these clearances are of the order of a tenth of a millimeter. The machining can therefore be effected with ordinary, inexpensive tools.

In accordance with the invention, the gasket 20 is in contact with the molten raw material 2, the crucible l, the nozzle means 3, 4, the cooling element 8 and the seal 23. The nozzle means 3, 4 is held in place axially by a part 26 which is screwed into the cooling element 8, as indicated at 26a. The part 26 may form a portion of the solidification chamber, which is not shown in this figure.

In the embodiment shown in FIG. 2, tightness between the pressurization enclosure 6 and the cooling element 8 is obtained by means of a seal 27, the assembly comprising these parts or elements being held in place by a part 28 which is bolted onto the pressurization enclosure 6 by bolts such as the one indicated at 28a.

As can be noted, the seals 23, 9 and 27 are placed in regions which are cooled. The result is that it is possible to employ ordinary, inexpensive seals which are nevertheless easily capable of withstanding relatively high pressures.

FIG. 3 shows how the inner orifice 24 of a nozzle is covered or masked by means of a masking packing 35 the end 30 of which is interposed between the nozzle and the raw material before and during the melting of the raw material 2 in the crucible 1. The solid phase of the material 2 is indicated at 2a. The gasket 35 has the shape of a cylinder provided with a bottom 30 at the end in contact with the raw material during the melting.

In the embodiment shown, the crucible 1 is insulated from the cooling element 8 by a layer of refractory, insulating material 36, shown in part. When the raw material has reached its melting point in the region adjacent the bottom 30 of the gasket, the bottom 30 ruptures, or, depending on the material of which it is made, it may disappear by melting or dissolving; the inner orifice 24 of the nozzle 3 is thus unmasked, and the jet 12 of molten raw material can be projected into the solidification chamber (not shown). As FIG. 6 shows, an agglomerate 60 of solidified material is then formed near the end 61 of the packing 35. This agglomerate caulks the clearance 63 between the crucible 1 (shown in part) and the nozzle means 3, 4. In the caulking zone, the material 2 extends without interruption of continuity from the liquid phase to the solid phase; the end 61 of the packing may be either clamped in the infiltrate of molten raw material 2 or welded upon the caulking.

The masking gasket 35 having the shape shown in FIG. 3 was used in an installation intended to project under a gaseous pressure of 40 bars a jet of liquid steel at a temperature between 1500 C. and 1600 C. into a cooling fluid. The gasket 35 had a length of 40 mm,

a diameter of 20 mm, and a thickness of 0.8 mm. It was produced by stamping from a sheet of soft or mild steel of 0.1% carbon. The clearance between the gasket and the nozzle means 3, 4 on the one hand, and the gasket and the wall of the crucible on the other hand, as well as between the gasket and the cooling element, was 0.1 to 0.2 mm in the cold state, so that'the initial spacing between the nozzle means 3, 4 and its housing in the crucible was 1.0 to 1.2 mm in the cold state.

FIG. 4 shows a flat masking gasket 40 arranged between the crucible 1 and the cooling element 8 (shown in part) on the one hand and the nozzle means 3, 4 and a fastening element 41 on the other hand. The cold seal 23 is arranged in a recess 42 provided in the cooling element 8.

FIG. 5 shows the use of a masking gasket in the form of a cup with wide rim 51.

FIG. 7, in a view similar to FIG. 2, shows an embodiment in which the gasket 20 is formed of an extension of the pressurization enclosure 6 which, in this case, also acts a cooling element having passage means 10 for the circulation of a cooling fluid.

Although apparatus has been shown in which the jet of molten raw material is directed vertically downward, the operation of apparatus comprising gaskets in accordance with the invention is independent of the direction of the jet in space.

Those skilled in the art will understand that the invention includes embodiments in addition to the representative ones disclosed above and is as broad as the appended claims and their equivalents.

I claim:

1. Apparatus for projecting a molten raw material into a cooling fluid to form a solid finished product therein, comprising a crucible for holding the raw material, nozzle means mounted for contact with the molten raw material in the crucible,

a pressurization enclosure for maintaining the raw material in the crucible under pressure,

gasket means formed of a material which is gas-tight and compatible with the molten raw material mounted for contact with the raw material and having a portion extending away therefrom,

the raw material facilitating a hot seal between (a) the portion of the gasket means in contact therewith and (b) the crucible and nozzle means, and means facilitating a cold seal between (a) the portion of the gasket means extending away from the raw material and (b) the pressurization enclosure.

2. Apparatus according to claim 1 further comprising cooling means for cooling the cold seal.

3. Apparatus according to claim 2 wherein the means facilitating the cold seal comprises a sealing material positioned between (a) the portion of the gasket means extending away from the raw material and (b) the cooling means.

4. Apparatus according to claim 1 wherein the gasket means is formed by an extension of the pressurization enclosure.

5. Apparatus according to claim 1 wherein the gasket means is formed of a metallic material.

6. Apparatus according to claim 1 wherein the gasket means is formed of a material substantially identical to the raw material.

7. Apparatus according to claim 1 wherein the raw material and the gasket means both comprise the same metal. t

8. Apparatus according to claim 1 wherein the means facilitating the cold seal comprises an elastic material.

9. Apparatus according to claim 1 wherein the means facilitating the cold seal comprises a metalloplastic material.

l0. Apparaus according to claim 1 wherein the means facilitating the cold seal comprises glue.

11. Apparatus according to claim 1 wherein the means facilitating the cold seal comprises solder.

12. Apparatus according to claim 1 wherein the gasket means has the shape of a body of revolution formed with a central opening.

13. Apparatus according to claim 1 wherein, before the apparatus is placed in operaton, the gasket means has the shape of a body of revolution formed without a central opening and masks the nozzle means.

14. Apparatus according to claim 13 wherein, after the apparatus is placed in operation, the gasket means has the shape of a body of revolution formed with a central opening.

15. Apparatus according to claim 2 wherein the cooling means is formed with a channel for the circulation of a cooling fluid.

16. Apparatus according to claim 1 wherein the raw material is steel and the gasket means is formed of soft steel.

17. Apparatus according to claim 1 wherein the nozzle means is oriented in such a manner as to project the raw material into the cooling fluid in a vertically downward direction. 

1. Apparatus for projecting a molten raw material into a cooling fluid to form a solid finished product therein, comprising a crucible for holding the raw material, nozzle means mounted for contact with the molten raw material in the crucible, a pressurization enclosure for maintaining the raw material in the crucible under pressure, gasket means formed of a material which is gas-tight and compatible with the molten raw material mounted for contact with the raw material and having a portion extending away therefrom, the raw material facilitating a hot seal between (a) the portion of the gasket means in contact therewith and (b) the crucible and nozzle means, and means facilitating a cold seal between (a) the portion of the gasket means extending away from the raw material and (b) the pressurization enclosure.
 2. Apparatus according to claim 1 further comprising cooling means for cooling the cold seal.
 3. Apparatus according to claim 2 wherein the means facilitating the cold seal comprises a sealing material positioned between (a) the portion of the gasket means extending away from the raw material and (b) the cooling means.
 4. Apparatus according to claim 1 wherein the gasket means is formed by an extension of the pressurization enclosure.
 5. Apparatus according to claim 1 wherein the gasket means is formed of a metallic material.
 6. Apparatus according to claim 1 wherein the gasket means is formed of a material substantially identical to the raw material.
 7. Apparatus according to claim 1 wherein the raw material and the gasket means both comprise the same metal.
 8. Apparatus according to claim 1 wherein the means facilitating the cOld seal comprises an elastic material.
 9. Apparatus according to claim 1 wherein the means facilitating the cold seal comprises a metalloplastic material.
 10. Apparaus according to claim 1 wherein the means facilitating the cold seal comprises glue.
 11. Apparatus according to claim 1 wherein the means facilitating the cold seal comprises solder.
 12. Apparatus according to claim 1 wherein the gasket means has the shape of a body of revolution formed with a central opening.
 13. Apparatus according to claim 1 wherein, before the apparatus is placed in operaton, the gasket means has the shape of a body of revolution formed without a central opening and masks the nozzle means.
 14. Apparatus according to claim 13 wherein, after the apparatus is placed in operation, the gasket means has the shape of a body of revolution formed with a central opening.
 15. Apparatus according to claim 2 wherein the cooling means is formed with a channel for the circulation of a cooling fluid.
 16. Apparatus according to claim 1 wherein the raw material is steel and the gasket means is formed of soft steel.
 17. Apparatus according to claim 1 wherein the nozzle means is oriented in such a manner as to project the raw material into the cooling fluid in a vertically downward direction. 